Eh~~ there was a chapter that implied Maine developing some feelings for Lutz though... ┑( ̄Д  ̄)┍ someone who would worry or even welled up for her when she gets slightly light headed, I see no problem in this relationship. Plus, the real question should be: are priestess even allow to get married in that world???
I'm telling you there is no such chapter, she even call him at the start "this child"... Lutz has his own dream, and Lutz doesn't have obligations to follow her forever... what happened here is Maine develop dependence to Lutz becoz of her sickly composition, in turn the obligation pass to future characters...
If following the novel....let say Lutz hv feelings for maine but he knows that maine can only be happy if she surrounded by books,so he like a protector for maine. He himself understand he can never be good enough for maine....
It's a shame,if only the mangaka didn't make maine insanely love book,then Luke may got a chance (seeing he wants to be a rich merchant) but then again,with Maine sickness (magic) Luke also understand he can't help Maine. So that probably the reason he let Maine go to the nobels....

I'm getting sick or maine attitude of obsessed with the books.
Is tiring (read the novel and ahead of this)
But I guess the one who poke her fingers to get blood is her future nobel sponsor?? (Just guessing since novel have not disclose it yet. But there is some relationship between those two. Beside,maine can't be a nobel wife because her status, she probably gonna be a concubine)
Not a shabby priest in terms of looks.
And he a hell lot mature from maine who supposedly a grown-up women from her previous life.